Saturday, November 21, 2009

I used to enjoy Douthat's old blog at the Atlantic, which I thought was a much better medium for him than the Times column. The thing about Douthat is that he's only any good when he's reacting to someone; it was a common feature, I think, of all his best posts on the old blog that they began with a longish quote from someone -- esp. his recurring sparring partners, Will Saletan, Damon Linker, and Will Wilkinson, all of whom are dumber and worse writers than Douthat. (Even if I agree with them more often.) His columns, by contrast, have been kind of flat and formulaic, and sometimes (the one about the "audacity of the pope") extremely silly. (His book reviews, on the other hand, are often good because he's reacting to the author.)

Anyway, he seems to be back to blogging, now at the NYT, and his blog is -- at least as of now -- a lot better than his columns.

Saturday, November 14, 2009

Gowers wants to do a Polymath project on the origin of life. This problem has been around for a long time now -- Schrodinger wrote a not-very-good book about it in his decadent Irish phase -- and part of the trouble with it is that it's hard to make precise. As Gowers explains, some statistical physicists have been trying to model life using sandpiles etc., with the working definition that "self-organized criticality" -- the persistence of structure on various length scales, hence some manner of fractal structure -- defines life. This is an unsatisfactory approach because (1) having order on various length scales does not imply fractality, which requires that the order must be the same, which isn't necessarily the case with life unless you buy some version of the Gaia hypothesis; (2) it presupposes a property of early organisms -- that they formed multilevel ecosystems -- that isn't a priori obvious. There are similar issues with Conway's game of life and some of the computer-science approaches that involve looking for self-generated Turing machines (!) in simple games.

On the whole I'm unconvinced that the problem is a good one for a mathematician (or physicist) at present, although -- like all semi-masturbatory projects -- it might stimulate developments in pure mathematics. The hard part is not finding an algorithm that generates "life" from the "primeval soup" for some definition of life and primeval soup; it is finding one that gets the gross features of real primitive life right. The existence proof is not the issue. One needs to think harder about testability than Gowers seems to want to: there are probably a gazillion different automata that give structures that are lifelike, but are any of them relevant to what happened in the primeval soup, and how would we know?

It's not obvious, either, that there is a math-problem/toy-model/"universal" aspect to biogenesis. As I understand the rough story, it goes something like this: given a primal soup with appropriate ingredients and dreadful weather, you can form (with some finite probability) a very primitive self-replicating strand of some (probably zipping) molecule. This is more or less what the Miller-Urey experiment suggests. The gaps in this story are essentially about rates -- would the amino acids survive for long enough to run into each other, what's the lifetime of an RNA strand, etc. -- and have no math content. The next question is how an RNA strand turns into a self-replicating proto-cell. Once again, this is mostly a question of rates; it's clear that a cell is more stable than a strand, once formed. There's a whiff of universality here -- for some simplified model of e.g. 3 cell ingredients, a spherical cell ingesting amino acid at a constant rate r etc., you can ask what the conditions are for life to be stable for long enough that cells can diffuse out -- they're unlikely to be motile at first -- into new environments before they suffocate in their own waste. In principle this might give you constraints on the origin of life. However, it seems exceedingly unlikely that a model of this kind would make testable nontrivial predictions. To get any further one would have to separate the essential and accidental features of the most primitive cells, and I'm not sure we're in a position to do that. The simplest organisms still existing today are wildly unrepresentative being the ones that survived.

I think Steven Pinker gives Gladwell more than his due, but his diagnosis here is spot on:

The banalities come from a gimmick that can be called the Straw We. First Gladwell disarmingly includes himself and the reader in a dubious consensus — for example, that “we” believe that jailing an executive will end corporate malfeasance, or that geniuses are invariably self-made prodigies or that eliminating a risk can make a system 100 percent safe. He then knocks it down with an ambiguous observation, such as that “risks are not easily manageable, accidents are not easily preventable.” As a generic statement, this is true but trite: of course many things can go wrong in a complex system, and of course people sometimes trade off safety for cost and convenience (we don’t drive to work wearing crash helmets in Mack trucks at 10 miles per hour). But as a more substantive claim that accident investigations are meaningless “rituals of reassurance” with no effect on safety, or that people have a “fundamental tendency to compensate for lower risks in one area by taking greater risks in another,” it is demonstrably false.

On the other hand, the structure described here is a paradigmatic strawman argument. One rarely knocks down a straw man for the sheer pleasure of it. The point of strawmanning is to introduce a counter-assertion that can be defended narrowly -- the "trite" version, which only an idiot, i.e. straw man or Gladwell's typical reader, would disagree with -- but is meant to sound like a broad (and usually indefensible) statement. And I must say that Pinker's evident irritation gives me some pleasure: this is, after all, a guy who straw-manned all of Western thought in The Blank Slate.

PS Gladwell's "igon values" reminded me of this old running joke Grobstein and I had about eigenworthlessness.

Friday, November 13, 2009

I need not explain why I was reading a list of school reunions, when my eye fell on what follows: the address of a girls' school in Llandudno, and the notification that it was the "Final Old Girls' Reunion". Next April it will occur; the information tolled in my ears: why is it the last, how can anyone know? It may be that the organiser has just got tired of doing all the work: that fewer and fewer old girls are turning up, that some of them are shrill and grubby and have vodka bottles in their bags, and piercings, and toyboys in tow: or that Llandudno is just too hard to get to. But sadder explanations suggest themselves. Are there only two old girls left, and has one of them been given a bad prognosis? I can't help thinking what it would be like, two sassy old dames crumbling a final scone together, replacing in its saucer the teacup drained of Darjeeling, polishing their noses with a crumpled tissue: "Well, Blinky, old thing . . ." "Well, Nodders, old girl . . ."; brushing crumbs from their laps, laying down the final butterknife, stepping into separate taxis to go their final ways. Surely there's a short story in it. But it's not mine, is it? It's one for Jane Gardam.

Wednesday, November 4, 2009

I think this is a rhetorical question. But consider these lines of poetry that Yeats wrote at some point in the 20th century:

I had a thought for no one's but your ears: That you were beautiful, and that I strove To love you in the old high way of love; That it had all seemed happy, and yet we'd grown As weary-hearted as that hollow moon.

The plainest, most straightforward language in the poem, in some ways, comes at the very end—final words, not uttered in the conversation, are more private and more urgent than what has come before. ... That closing passage of interior thoughts [...] makes the poem feel, to me, as though not simply heard but overheard.

... how artificial Yeats's manner of writing was. As a rule, this artificiality is accepted as Irishism, or Yeats is even credited with simplicity because he uses short words, but in fact one seldom comes on six consecutive lines of his verse in which there is not an archaism or an affected turn of speech.

Monday, November 2, 2009

Went to a talk by ex-BBC producer Roy Davies today, about his new book The Darwin Conspiracy, which supposedly proves that Darwin stole Alfred Russel Wallace's ideas rather than coming up with them independently. Davies' argument in the talk was three-pronged: (1) Darwin was provably mendacious, (2) Darwin's 1840s work on evolution was entirely wrongheaded, and there's no reason to believe that he was on the right track before Wallace's letters reached him, and (3) Darwin lied about when Wallace's letters reached him, on the evidence of a bunch of 1850s Indonesian naval timetables that show when the mailboats came and went from wherever Wallace was at the time. Davies' work seems either comprehensively false or largely correct, as his story hangs together quite well. I have no idea of how sound the detective work on (3) is, but if (1) and (2) are true then (3) is plausible anyway. The main evidence for (1) is that Darwin silently edited his Beagle diaries between the 1839 edition and the 1844 edition to insert a bunch of material semi-plagiarized from Edward Blyth and possibly Vestiges of Creation. As for (2), Davies claims that Darwin's 1840s work on evolution was mostly based on the idea that species swam across the sea and found themselves in new surroundings where they had "somehow" to adapt to survive; and that Darwin hadn't thought of survival of the fittest at this point. As someone who's utterly unfamiliar with 19th-century biology, I'm curious to know if Davies is entirely making this up.

As for how this fits into the larger picture, it's of no consequence whether Darwin or Wallace came up with the theory of evolution, or whether Darwin was a crook. But it's always seemed to me -- and here of course I differ from Davies -- that Darwin/Wallace get way too much relative credit for their contributions to evolutionary theory. The story as I see it goes something like this:

1. Early 1800s geologists find out that the geography of the earth changes over time, sometimes relatively fast. The earth appears to be pretty old. Native species seem well-adapted to their changing environments; this is implausible in the extreme if everything was created at once. Therefore, some sort of adaptation must happen. Also, there are fossils.

2. The species native to some (old) islands are highly distinctive, whereas those from recently isolated islands are similar to the mainland varieties. The pattern of similarities in archipelagoes, in particular, -- Indonesia, the Galapagos -- seems strongly suggestive of a common ancestor from whom the varieties diverged over time because they were isolated. This gets you the "descent with modification" part.

3. A half-assed analogy with Malthus leads to the claim that descent with modification is due to "survival of the fittest" while competing for scarce resources. This claim was largely unsubstantiated (it's more a conjecture than anything else) and had huge problems, e.g., that with "blending inheritance" -- the naive belief that characteristics "blend" during reproduction, which I think everyone believed at the time -- mutations are unlikely to survive.

4. Gregor Mendel discovers that inheritance is particulate rather than blending, i.e., that black + black = white 1/4 of the time, and basically invents genetics. I don't know if Mendel thought about the implications for evolution, but this is really the key point that makes natural selection work.

5. 20th-century geneticists -- people like Morgan, Fisher, and Haldane -- turn genetics into a proper experimental science and construct the theory of evolution through natural selection, or, if you like, prove Darwin's conjecture using Mendel's theory.

In terms of importance I would rank these 4-1-5=2-3 -- and that's without discounting 3. as derivative of Malthus. First of all, 3. is conceptually shaky without 4., and vague besides; this is evident from e.g., the fact that the next major advances in evolutionary theory came through 4. via 5. This is rarely the case with true scientific breakthroughs. Second, I feel like 4. would have led immediately to 3. once people started taking Mendel seriously. This is because 1. and 2. had opened up the question of the variation of species (which is why they are important advances).

It would be a gross exaggeration to say that Darwin discovered evolution like Democritus discovered atoms, but not, I suspect, a complete falsehood.

PS Wallace was a spiritualist and a teleologically minded type so it's probably a good thing he didn't grow too influential. Besides, he was no Marsellus Wallace.